Electronic instrument for refrigerant recovery machine

ABSTRACT

Used in a refrigerant recovery machine having a refrigerant input pipe and a refrigerant output pipe, an electronic instrument is disclosed to include a control unit, a LCD device controllable by the control unit to display the operation status of the refrigerant recovery machine, and a pressure sensor unit having an input pipe pressure sensor and an output pipe pressure sensor for detecting the pressure in the input pipe and the pressure in the output pipe and transmitting the respective detected pressure values to the control unit for comparison with a pre-set pressure threshold limit value so that the control unit controls the operation of the refrigerant recovery machine subject to the comparison results.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to refrigerant recovery technology and more particularly, to an electronic instrument for use in a refrigerant recovery machine to control the operation of the refrigerant recovery machine in collecting the refrigerant from the main unit of a cooler or refrigerator.

2. Description of the Related Art

A refrigerant recovery machine is adapted to draw the refrigerant out of the main unit of a system (room cooler, car cooler, central air conditioning system or refrigerator) into a recovery tank. However, a conventional refrigerant recovery machine must be equipped with an extra high-pressure mechanical type safety pressure switch and an extra mechanical vacuum type safety pressure switch. These two safety switches are respectively connected to the valve blocks in the refrigerant input pipe and refrigerant output pipe of the refrigerant recovery machine. When the input or output pressure of the refrigerant recovery machine surpasses a respective predetermined pressure threshold limit value, the respective safety switch switches off the refrigerant recovery machine, assuring operational safety. However, these mechanical safety switches have a broad range of pressure error and tend to cause an incomplete refrigerant drawing problem. Further, these mechanical safety switches are commonly heavy and expensive, increasing the cost of the refrigerant recovery machine and complicating the installation of the piping.

Further, during the operation of a refrigerant recovery machine, the pipes of the refrigerant recovery machine may be clogged with the dirty refrigerant. Clogging of the pipes may cause freezing of the refrigerant, resulting in an abnormal pressure value and affecting the drawing of the refrigerant.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide an electronic instrument for refrigerant recovery machine, which detects the pressure of the pipes in the refrigerant recovery machine and compares the detected pressure values with predetermined pressure threshold limit values, and then controls the operation of the refrigerant recovery machine subject to the pressure comparison results, enabling the refrigerant recovery machine to draw the refrigerant from the main unit of a refrigerator or cooler accurately and safely.

It is another object of the present invention to provide an electronic instrument for refrigerant recovery machine, which detects the temperature of the pipes in the refrigerant recovery machine and compares the detected temperature values with a predetermined temperature threshold limit value, and then controls the operation of the refrigerant recovery machine subject to the temperature comparison result, enabling the refrigerant recovery machine to draw the refrigerant from the main unit of a refrigerator or cooler accurately and safely.

To achieve these and other objects of the present invention, an electronic instrument is used in a refrigerant recovery machine comprising a refrigerant pipe system having an input pipe and an output pipe, a compressor pipe line and a condenser pipe line. The electronic instrument comprises a control unit, a LCD device controllable by the control unit to display the operation status of the refrigerant recovery machine, a pressure sensor unit and a temperature sensor unit for detecting the pressure in the input pipe and the output pipe and the temperature in the input pipe, the output pipe, the compressor pipe line and the condenser pipe line and transmitting the respective detected pressure and temperature values to the control unit for comparison with pre-set pressure threshold limit values and temperature threshold limit values so that the control unit controls the operation of the refrigerant recovery machine subject to the comparison results.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a refrigerant recovery machine carrying an electronic instrument in accordance with the present invention.

FIG. 2 is a system block diagram of the refrigerant recovery machine shown in FIG. 1.

FIG. 3 is a system block diagram of the electronic instrument in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-3, a refrigerant recovery machine 1 is shown carrying an electronic instrument 2. The refrigerant recovery machine 1 has mounted therein a refrigerant pipe system 11, a compressor pipe line 12 and a condenser pipe line 13. The refrigerant pipe system 11 comprises an input pipe 111 and an output pipe 112. Valve switches 14 are respectively in the input pipe 111 and the output pipe 112 for controlling closing/opening of the respective passages. The electronic instrument 2 comprises a control unit 21, a LCD (Liquid Crystal Display) device 22, a pressure sensor unit 23, a temperature sensor unit 24, operating buttons 25 and an alarm 26. The LCD (Liquid Crystal Display) device 22, the pressure sensor unit 23, the temperature sensor unit 24, the operating buttons 25 and the alarm 26 are respectively electrically connected to the control unit 21.

The control unit 21 comprises a microprocessor 211, a multiplexer 212 and an operation amplifier 213. The microprocessor 211 has set therein pressure threshold limit values and a temperature threshold limit value. The pressure threshold limit values include a high-pressure threshold limit value and a negative pressure (vacuum) threshold limit value.

The LCD device 22 is controllable by the control unit 21 and adapted to display status data of the refrigerant recovery machine 1 transmitted by the control unit 21.

The pressure sensor unit 23 comprises an input pipe pressure sensor 231 adapted to detect the pressure in the input pipe 111 of the refrigerant pipe system 11 of the refrigerant recovery machine 1, and an output pipe pressure sensor 232 adapted to detect the pressure in the output pipe 112 of the refrigerant pipe system 11 of the refrigerant recovery machine 1.

The temperature sensor unit 24 comprises an input pipe temperature sensor 241 adapted to detect the temperature in the input pipe 111 of the refrigerant pipe system 11 of the refrigerant recovery machine 1, an output pipe temperature sensor 242 adapted to detect the temperature in the output pipe 112 of the refrigerant pipe system 11 of the refrigerant recovery machine 1, a compressor pipe line temperature sensor 243 adapted to detect the temperature in the compressor pipe line 12 and a condenser pipe line temperature sensor 244 adapted to detect the temperature in the condenser pipe line 13.

The operating buttons 25 are operable by the user to control the control unit 21 in controlling the operation of the refrigerant recovery machine 1 and the display mode of the LCD device 22.

The alarm 26 is controlled by the control unit 21. When the refrigerant recovery machine 1 is abnormal or fails, the alarm 26 gives a warning signal. The alarm 26 can be a buzzer or light source.

When using the refrigerant recovery machine 1 to draw in the refrigerant from the system main unit, switch off the valve switches 14 of the refrigerant recovery machine 1 to close the input pipe 111 and the temperature in the output pipe 112, and then connect the input pipe 111 to the system main unit and the output pipe 112 to a refrigerant storage tank. At this time, the user can operate the operation buttons 25 to start the refrigerant recovery machine 1 and then switch on the valve switches 14 of the refrigerant recovery machine 1 to open the input pipe 111 and the temperature in the output pipe 112. During operation of the refrigerant recovery machine 1, the refrigerant of the system main unit is drawn by the refrigerant recovery machine 1 into the input pipe 111 to flow through the compressor pipe line 12 and the condenser pipe line 13 toward the refrigerant storage tank via the output pipe 112. When the refrigerant recovery machine 1 is drawing the refrigerant out of the system main unit toward the refrigerant storage tank, the input pipe pressure sensor 231 and the output pipe pressure sensor 232 keep detecting the pressure in the input pipe 111 and the pressure in the output pipe 112 respectively and provides the respective detected pressure values to the control unit 21 for comparison with the set pressure threshold limit values. Because the refrigerant is being drawn out of the system main unit into the input pipe 111, the inside pressure of the system main unit is continuously lowered, producing a vacuum. Thus, when the control unit 21 receives a pressure value from the input pipe pressure sensor 231, the microprocessor 211 compares the pressure value with the set negative pressure (vacuum) threshold limit value. When the detected pressure value is equal to or below the set negative pressure (vacuum) threshold limit value, it means the refrigerant has been completely drawn out of the system main unit. At this time, the control unit 21 drives the LCD device 22 to display the message and the alarm 26 to give an alarm signal, and then stops the refrigerant recovery machine 1. Because the output pipe 112 delivers the refrigerant to the refrigerant storage tank, the pressure in the refrigerant storage tank will increase gradually. When the control unit 21 receives a pressure value from the output pipe pressure sensor 232, the microprocessor 211 compares the pressure value with the set high pressure threshold limit value. When the detected pressure value is equal to or above the set high pressure threshold limit value, it means the storage amount of the refrigerant in the refrigerant storage tank has reached to the desired level. At this time, the control unit 21 stops the operation of the refrigerant recovery machine 1 (if the refrigerant recovery machine 1 is not stopped at this time, the refrigerant storage tank may be unable to sustain the pressure and may break or the collected refrigerant may leaks through the relief valve to pollute the air) and drives the LCD device 22 to display the message and the alarm 26 to give an alarm signal. After replacement of the refrigerant storage tank that is fully filled up with the refrigerant with an empty refrigerant storage tank by the user, the pressure detected by the output pipe pressure sensor 232 will be below the set high pressure threshold limit value, enabling the control unit 21 to start the refrigerant recovery machine 1 and to draw the refrigerant out of the system main unit again. The user can also operate the operation buttons 25 to start the refrigerant recovery machine 1 after replacement of the refrigerant storage tank that is fully filled up with the refrigerant with an empty refrigerant storage tank. During operation of the refrigerant recovery machine 1, the input pipe temperature sensor 241, output pipe temperature sensor 242, compressor pipe line temperature sensor 243 and condenser pipe line temperature sensor 244 of the temperature sensor unit 24 detect the temperature in the input pipe 111 and output pipe 112 of the refrigerant pipe system 11 of the refrigerant recovery machine 1 and the temperature in the compressor pipe line 12 and the temperature in the condenser pipe line 13 respectively and transmit the respective detected temperature values to the control unit 21 so that the microprocessor 211 of the control unit 21 compares the received temperature values with the set temperature threshold limit value. When the detected temperature value from the input pipe temperature sensor 241, the output pipe temperature sensor 242, the compressor pipe line temperature sensor 243 or the condenser pipe line temperature sensor 244 is equal to or below the set temperature threshold limit value, it means the corresponding pipe line is a frozen status to block transfer of the refrigerant. Therefore, the control unit 21 stops the refrigerant recovery machine 1 and drives the LCD device 22 to display the message and the alarm 26 to give an alarm signal when the detected temperature value from the input pipe temperature sensor 241, the output pipe temperature sensor 242, the compressor pipe line temperature sensor 243 or the condenser pipe line temperature sensor 244 is equal to or below the set temperature threshold limit value. After the trouble is eliminated and the temperature resumes normal, the control unit 21 starts the refrigerant recovery machine 1 again. Further, the microprocessor 211 has set therein an abnormality detection temperature value. When the detected temperature value from the compressor pipe line temperature sensor 243 or the condenser pipe line temperature sensor 244 reaches the set abnormality detection temperature value, it means the compressor pipe line 12 or the condenser pipe line 13 has broken or there is a refrigerant leakage. At this time, the control unit 21 stops the refrigerant recovery machine 1 and drives the LCD device 22 to display the message and the alarm 26 to give an alarm signal.

In conclusion, the invention utilizes the pressure sensor unit 23 and temperature sensor unit 24 of the electronic instrument 2 to detect the refrigerant drawing status and the control unit 21 to control the operation of the refrigerant recovery machine 1 subject to the results of comparison of the detected values from the pressure sensor unit 23 and the temperature sensor unit 24 with predetermined pressure and temperature threshold limit values, eliminating the use of high-pressure mechanical type and mechanical vacuum type safety pressure switch means as seen in the prior art techniques, reducing the cost and dimension of the refrigerant recovery machine 1.

Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. 

1. An electronic instrument used in a refrigerant recovery machine comprising a refrigerant pipe system, a compressor pipe line and a condenser pipe line, said refrigerant pipe system having an input pipe and an output pipe, the electronic instrument comprising: a control unit for controlling the operation of said refrigerant recovery machine, said control unit comprising a microprocessor having set therein at least one pressure threshold limit value; a liquid crystal display device electrically connected to said control unit and controllable by said control unit to display status of said refrigerant recovery machine; and a pressure sensor unit electrically connected to said control unit, said pressure sensor unit comprising an input pipe pressure sensor adapted to detect the pressure in said input pipe and to transmit the detected temperature value to said control unit for comparison with one said pressure threshold limit value and an output pipe pressure sensor adapted to detect the pressure in said input pipe and to transmit the detected temperature value to said control unit for comparison with one said pressure threshold limit value.
 2. The electronic instrument as claimed in claim 1, wherein said at least one pressure threshold limit value comprises a high-pressure threshold limit value and a negative pressure threshold limit value.
 3. The electronic instrument as claimed in claim 1, further comprising a temperature sensor unit electrically connected to said microprocessor of said control unit, said temperature sensor unit comprising an input pipe temperature sensor adapted to detect the temperature in said input pipe and to transmit the detected temperature value to said microprocessor for comparison with a predetermined temperature threshold limit value set in said microprocessor, an output pipe temperature sensor adapted to detect the temperature in said output pipe and to transmit the detected temperature value to said microprocessor for comparison with said predetermined temperature threshold limit value, a compressor pipe line temperature sensor adapted to detect the temperature in said compressor pipe line and to transmit the detected temperature value to said microprocessor for comparison with said predetermined temperature threshold limit value and a condenser pipe line temperature sensor adapted to detect the temperature in said condenser pipe line and to transmit the detected temperature value to said microprocessor for comparison with said predetermined temperature threshold limit value. 